Fixed a bug in RateLimitExceeded with incorrect key to response dict

[north1]

RateLimitExceeded.init was setting sleep_time to response['ratelimit'] which was throwing a KeyError exception every time I hit it. Swtiched to 'delay' which seemed to fix the functionality.

If this isn't correct, ignore this, but it fixed my problem and I thought I'd share it.

If this isn't the correct branch to send the pull request to but the fix should still be pulled, please let me know.

[bboe]

We'll have to confirm that it was changed on the server side before accepting.

[north1]

Sounds good :) My own code was throwing that error enough that I noticed the problem.

[bboe]

The code here leads me to believe that the item name is still ratelimit (FYI: I added that code on reddit's side): https://github.com/reddit/reddit/blob/master/r2/r2/lib/jsonresponse.py#L65

Can you reproduce the problem and provide a log? Perhaps you're hitting something else.

[north1]

Alright, sorry I couldn't get to this yesterday. Bug is very reproduceable. Try running this script:

import praw
r = praw.Reddit(user_agent='rate limit test by /u/neph001')
while(not r.is_logged_in()):
    try:
        r.login('a', 'a')
    except praw.errors.InvalidUserPass:
        pass

Give it a few seconds, and it crashes throwing this error:

Traceback (most recent call last):
  File "/home/neph/PycharmProjects/praw_ratelimit/praw_ratelimit.py", line 9, in <module>
    r.login('a', 'a')
  File "/usr/local/lib/python2.7/dist-packages/praw/__init__.py", line 1157, in login
    self.request_json(self.config['login'], data=data)
  File "/usr/local/lib/python2.7/dist-packages/praw/decorators.py", line 172, in wrapped
    return_value))
  File "/usr/local/lib/python2.7/dist-packages/praw/errors.py", line 325, in __init__
    self.sleep_time = self.response['ratelimit']
KeyError: 'ratelimit'

So I went in and ran PyCharm's debugger to take a look at the errors source code as the error is thrown, and the response dict appears to look like this:

response={u'errors': [[u'RATELIMIT', u'you are doing that too much. try again in 3 minutes.', u'vdelay']]}

Which is weird because the RateLimitExceeded class is trying to assign response['ratelimit'] to RateLimitExceeded.sleep_time, which I'm fairly certain is used as an int.

Thoughts? Am I missing something obvious?

[bboe]

I see. This appears to be an inconsistency on reddit's end as I wrote PRAW's rate limit error handling functionality for submission and comments occurring too often. It appears the login rate limiting behaves differently. I'll look into it a bit.

[bboe]

Relevant IRC discussion: https://botbot.me/freenode/reddit-dev/msg/9889683/

@Deimos said he'll look into it.

[north1]

Cool! Well even if my 'fix' isn't helpful, I'm glad that I pointed out an actual bug and I wasn't just crazy. I would like to reiterate that when I changed my own copy of praw to use 'delay' instead of 'ratelimit' it did fix this issue for me, though now I suspect it also broke the RateLimitExceeded error for other limits (comments, etc). I might test that for fun.

In any case if there's anything else I can do to help, I'd be happy to. I'd like to stay in the loop at least.

[tjvezina]

Hi there - I'm having the exact same issue and error output as north1 mentioned above. I'm using PRAW for a bot that's been running for about a week and a half now without any problems, but about an hour ago I started to get this KeyError: 'ratelimit' issue. I tried north1's fix by swapping 'ratelimit' out for 'delay', but I just get the same crash and error.

I know the potential difference between login ratelimits and post/comment ratelimits is being looked into, but is there a short-term solution to this so I can keep my bot running? I tried taking it offline for 30 minutes but it continues to get the error as soon as I start it up again.

[north1]

tjvezina: Is your bot having this error thrown for logging in and out too much? If so...why is it doing that?

I ended up finding this because I was developing a desktop application and I was testing part of the script where it should keep asking for you to log in again if you pass it the wrong credentials, but I'd imagine you'd hard code the correct credentials into the bot and just keep it logged in?

In any case, there is certainly a short term solution: use a Try/Except to catch the KeyError exception.

[tjvezina]

This bot is running on Google App Engine, I got a sort of "template" from another mod, which sends an HTML request to the bot every 2 minutes, at which point it logs in, performs its intended tasks, and then exits.

I'm not sure if there's any way I could have a single instance running continuously, instead of a new instance every 2 minutes that only lives for ~15 seconds. My concern then would be if that single instance crashed, in which case it would stay crashed until I found out and manually launched another instance, I think.

As for the try/except idea, I threw that in for now, and it does stop the crashing, but of course the bot is still failing to log in.

[north1]

Well, it should eventually succeed when the ratelimit is no longer exceeded, which I think is what would happen even if this bug were not present. In both your case and mine, an error being thrown is the correct functionality.

This bug (and this pull request) is that, due to an error within the source code for the error (technically within Reddit's source code it seems, not PRAW's) the wrong error is being thrown. Praw already has a built in handler for the RateLimitExceeded exception that will wait the given amount of time to try again automatically (I think - bboe will have to back me up here or correct me) but in the case of login, Reddit's API handles things a bit incongruously.

My suggestion is to, catching the KeyError exception, manually wait through the delay time. You can do this without changing anything by just...letting it log in again on the next pass in 2 minutes.

[tjvezina]

That's a very a good idea. The version I have running right now seems to occasionally work (about once every 3 instances) which is much better than nothing. I'll try getting it to manually wait out the ratelimit in a bit - thanks for the help!

[tjvezina]

Hi there, me again - over the past week my bot has been bouncing between successfully running and getting the same 'ratelimit' KeyError as always when attempting to log in. Yesterday it totally flat-lined and repeatedly got the KeyError for about 12 hours, rendering the bot useless.

I took it offline yesterday afternoon, rewrote it to only need one login per day, and attempted to re-deploy this morning, only to hit the same KeyError as always (after 13 hours offline). I'm not exactly sure what I'm looking for now, but I guess I have 2 questions:

Since I'm getting this KeyError: 'ratelimit' error instead of a proper ExceededRateLimit error, is there any way to figure out how long reddit is trying to tell my bot to wait before logging in again?

And more generally, any ideas about why I'm getting so many of these errors, even after being offline so long?

Thanks again for all your help!

[bboe]

In my experience you should only get login rate-limited if you are entering the wrong password. If this is your bot, there is no reason for that to occur. My only other speculation is that you are starting too many instances of the bot at one time. If you're running more than one concurrent instance, then you should make use of praw-multiprocess.

[tjvezina]

Yeah, it definitely has the correct password, and there's only ever one instance running (a new instance is created every 2 minutes, which typically takes 15-20 seconds to complete execution). I've even experimented with a different version of the bot that only signs in once and executes in an infinite loop, sleeping for 2 minutes between rounds, but same problem.

I've even created a whole new application under Google App Engine, created a brand new reddit account for the bot (verified email and all), and launched the rewritten version of my python script, but it somehow still gets the KeyError every time I launch an instance.

Another thing is, I'm able to test the bot through localhost just fine, but the error returns as soon as it goes live. Is it possible that reddit has somehow blocked the application on Google App Engine via IP address or somesuch?

[bboe]

Yes, accessing reddit's API via GAE has a number of restrictions as it proxies external requests through only a few IPs. I would suggest talking with someone on #reddit-dev in IRC (freenode).

Here's my suggestion: Cookies for reddit users are valid indefinitely until a password change occurs (or the logout all other sessions feature is utilized). Adjust your bot to never login; just manually set the cookie. Then you shouldn't have to worry about this problem.

[Damgaard]

You might be under heavier API restrictions if you are sending requests from a GAE server. Reddit's API restrictions are both on a per user and per IP basis. The precise details of this is unknown, the anti-spammer code is closed source. But if there are other programs on GAE accessing reddit, then you could be under much heavier restrictions. It would be a bit extreme if that's the case, but considering some of the other weird things we've encountered with GAE it wouldn't surprise me.

Have you considered using Heroku instead? I know there's quite a few people using it to host their bots/scripts for it, but we've never had a single bug, issue or even question related to Heroku. It seems it just works. The guy responsible for python stuff at Heroku is the same guy who wrote the requests library that PRAW uses to send and receive internet messages. So it's no surprise that it works so well there.

[tjvezina]

@bboe That's good to know. I get what you're saying about the cookies - I have no idea how to implement that but it's definitely something to look into, and I'll check out the IRC channel after work, thanks!

@Damgaard I've never heard of Heroku, I just signed up and started looking though the docs. It looks pretty interesting, and if it's already hosting other bots, hopefully I can get it worked for me as well.

[bboe]

Hopefully Heroku will work for you. I added #278 so that we can make dealing with cookies simpler.

[north1]

@bboe: Back on topic, has there been any updates regarding the original discrepancy between how ratelimit works with submissions and comments, and how it works with logins? I feel like I should stay on top of the issue and help however I can since I'm the dude who found it.

If you're curious how I found it (or how I failed to log in that many times in the first place) it's not a bot. I've been working on this project and was testing that the login handler worked correctly, since it needs to handle human input an not a hard coded username/password.

[Damgaard]

It looks like no solution is coming upstream in the near future, so we should get a workaround in PRAW. Exceptions crashing is not excatly userfriendly. Since we still expect most responses to contain the 'ratelimit' variable, I don't think we should replace it with 'delay', which is only good for this particular case. Here is what I propose

        # Login ratelimits throw a special form of this exception, with the sleep_time
        # given in the "delay" variable instead. See https://github.com/praw-dev/praw/pull/276
        # for more information.
        if "delay" in self.response:
            self.sleep_time = self.response['delay']
        else:
            self.sleep_time = self.response['ratelimit']

With an entry in the changelog as well.

[north1]

That looks acceptable. Super weird that this ever even came up at all.

[bboe]

@north1 can you confirm that this is still an issue?

@Damgaard were you ever able to reproduce the problem?

[bboe]

I was able to reproduce the problem (too many invalid login attempts) so I'll merge this stuff.

[bboe]

Actually, I have a response that does not contain the 'ratelimit' field, but it also does not have a 'delay' field. In what cases does a 'delay' value appear?

[bboe]

Fixed on reddit's end with respect to rate limiting on login. No need for a PRAW update. I couldn't find anything that indicates a delay field. Please create a new issue if something like that comes up. Thanks for reporting!

[bboe]

reddit-archive/reddit@e4a2d38

The fix on reddit's end for reference.